The project involves an estimation of the numbers and Bratthall serologic types of Streptococcus mutans obtained from a variety of the patients seen in the dental clinic. The presence of S. mutans and S. mutans serotypes are to be related to the clinical manifestations of caries in these patients. From this information we hope to gain further insight about the specificity of this suspected odontopath. Other data available from patient records, such as demographic information, manifestations of other diseases, and the presence or absence of specific medication or therapy will be used to develop a better understanding of the ecology of the organism. The systematics of the natural isolates identified as S. mutans will be studied intensively in an attempt to determine the significance of the Bratthall classification and its clinical implications.